With the design trend in electronic devices is toward lighter, smaller, thinner but more functional devices with performance requirements continuing to increase, device manufacturers increasingly need specialty integrated circuit (IC) solutions for allowing billions of miniature electronic components to be densely packed in a small area. Thus, device manufacturers come up with innovative packaging techniques for embedding electronic components in a substrate while allowing shorter traces between the electronic components and the substrate. In addition, the layout area is increased by the use of built-up technique as the technology advances for achieving lighter, smaller, thinner and more functional high-performance devices.
Generally, most high-end chips are packaged by flip chip (FC) process, especially by a chip scale package (CSP) process, as those high-end chips are primarily being applied in smart phones, tablet computers, network communication devices, and notebook computers, whichever is generally operating under high-frequency and high-speed condition and required to be packed in a thin, small and light-weighted semiconductor package. As for the carrier for packaging, the popular design nowadays includes: small pitches between lines, high density, thin-type design, low manufacture cost, and high electrical characteristic.
Please refer to FIG. 1, which shows a conventional fiberglass substrate packaging structure. In FIG. 1, the fiberglass substrate packaging structure 10 has a fiberglass substrate 100, which can be made of a bismaleimide triazine (BT) substrate or FR-5 substrate. In addition, the fiberglass substrate 100 is formed with a groove 110 and a plurality of via holes 120 by a laser via method, by that the groove 110 can be used for receiving and holding an electronic component 130, while a portion of the plural via holes 120 can be provided for receiving a conductive metal pillar 140. As shown in FIG. 1, the two first conductive metal layers 142, 144 are respectively disposed on the fiberglass substrate 100 while allowing the two to connected electrically to the conductive metal pillar 140; the groove 110 and the electronic component 130 are covered and sealed by an insulation layer 150, whereas the electronic component 130, the plural via holes 120, two second conductive metal layers 146, 148 to be disposed on the insulation layer 150 while being connected electrically to the electronic component 130 and the two first conductive metal layers 142, 144.
However, the aforesaid conventional fiberglass substrate packaging structure is disadvantageous in that: it can be very costly for using a fiberglass substrate as its substrate in addition to that the thin-type fiberglass substrate can be easily deformed and wrapped, and the conventional substrate including fiberglass will increase the difficulty of processing for laser via so that it cannot fit the need of fine pitch therefore make the wiring more troublesome; and as the blind/buried vias in the aforesaid four-layered metal laminated structure are formed by the repetition of a laser via method, such repetition can be a complex and time consuming process and also the cost for fabricating the four-layered metal laminated structure can be costly. Therefore, the aforesaid conventional fiberglass substrate packaging structure does not have industrial advantages.
Please refer to FIG. 2, which shows a conventional molding compound substrate packaging structure. As shown in FIG. 2, the molding compound substrate packaging structure 20 includes: a first wiring layer 200, a metal layer 210, a pillar conductive layer 220, a molding compound layer 230, a second wiring layer 240, and a protection layer 250. In which the first wiring layer 200 has a top surface and a bottom surface that are arranged opposite to each other; the metal layer 210 is disposed on the bottom surface of the first wiring layer 200; the pillar conductive layer 220 is disposed on the top surface of the first wiring layer 200; the molding compound layer 230 is disposed on the first wiring layer 200 and the pillar conductive layer 220 without having the molding compound layer 230 to be exposed out of the bottom surface of the first wiring layer 200 and one end of the pillar conductive layer 220; the second wiring layer 240 is disposed on the molding compound layer 230 and one end of the pillar conductive layer 220; the protection layer 250 is disposed on the molding compound layer 230 and the second wiring layer 240.
Since the aforesaid conventional molding compound substrate packaging structure is made of a molding compound material and the electrical connection between the plural wiring layers formed therein is achieved by the conduction of the pillar conductive layer instead of the laser via holes on the aforesaid fiberglass substrate packaging structure, the molding compound substrate packaging structure can have better rigidity than the fiberglass substrate by that it is less likely to deform and wrap than the fiberglass substrate. However, the good rigidity of such molding compound substrate can come with a cost that it is easy to crack and break into pieces, causing irretrievable problems of poor reliability and interruption in electrical connection which can be especially severe for thin-type molding compound substrates. In addition, as the pillar conductive layer for such molding compound substrate is formed directly on the bonding pads of its first wiring layer occupying the space of substrate, it might not be applied for products of fine pitch design, and also for those products with stacking structure, their manufacturing process can be difficult and costly since there can be more than one pillar conductive layer while the pillar in each pillar conductive layer will be required to be formed thinner and thinner.